Preheat the oven to 350 degrees F.
In a large bowl, combine all the guacamole ingredients and mix well. Put in an airtight container and refrigerate until ready to use.
On a large baking sheet, place the tortillas. Spray them with the cooking spray.
Bake for 3-5 minutes, remove, flip the tortillas, and bake for an additional 3-5 minutes.
Add the guacamole to the tostada, then add the toppings.
Top with the dressing, serve, and enjoy!